week 1 treatment planning

Keys steps of treatment planning

1. Prescription- The physician determines the radiation dose and treatment area.

2. Planning - Experts create a precise plan for safe and effective dose delivery.

3. Treatment - The plan is executed to deliver radiation to the patient.

• Planning Process Overview

•Goal: Customize and optimize radiation treatment for each patient.

•Uses:

Machine settings + patient data + calculations.

Collect Patient Data

•CT scan, tumor location, and critical structures.

Machine & Beam Data

•Radiation quality, PDD, beam profiles.

•Source or beam placement optimization.

• Required Patient Information for Treatment Planning

• Radiation therapy is localized → Focuses on a specific area.

• Target details → Location, volume, and shape of the tumor.

• Secondary targets → Any nearby areas that also need treatment.

• Critical structures → Important organs/tissues to protect.

• Radiobiology → How radiation affects tumor and normal tissues.

• Dose AND volume → Amount of radiation needed for both tumor and normal structures.

Target Volumes (ICRU Standard)

•Purpose:

Standardizes treatment planning & allows comparison across cancer centers.

GTV

Gross Tumor Volume) → Visible or palpable tumor.

CTV

Clinical Target Volume) → EXPANDS from GTV + microscopic disease (possible spread).

PTV

Planning Target Volume) → CTV + margins (for setup uncertainties).

ITV

Internal Target Volume) → CTV + internal motion margins (e.g., breathing).

Treated Volume

Area that actually gets the prescribed dose.

How quickly a tumor grows depends on 3 factors

Division rate of cells proliferation

Growth factor

Degree of cell death- exfoliation death